Make from_{hex,base32z,base64} compatible with std::byte

Make the char handling a bit more generic so that std::byte (or other
size-1 types) will work.

lokimq/base32z.h

@@ -75,7 +75,7 @@ static_assert(b32z_lut.from_b32z('w') == 20 && b32z_lut.from_b32z('T') == 17 &&
 /// Converts bytes into a base32z encoded character sequence.
 template <typename InputIt, typename OutputIt>
 void to_base32z(InputIt begin, InputIt end, OutputIt out) {
-    static_assert(sizeof(*begin) == 1, "to_base32z requires chars/bytes");
+    static_assert(sizeof(decltype(*begin)) == 1, "to_base32z requires chars/bytes");
     int bits = 0; // Tracks the number of unconsumed bits held in r, will always be in [0, 4]
     std::uint_fast16_t r = 0;
     while (begin != end) {
@@ -113,9 +113,9 @@ inline std::string to_base32z(std::string_view s) { return to_base32z<>(s); }
 /// Returns true if all elements in the range are base32z characters
 template <typename It>
 constexpr bool is_base32z(It begin, It end) {
-    static_assert(sizeof(*begin) == 1, "is_base32z requires chars/bytes");
+    static_assert(sizeof(decltype(*begin)) == 1, "is_base32z requires chars/bytes");
     for (; begin != end; ++begin) {
-        auto c = *begin;
+        auto c = static_cast<unsigned char>(*begin);
         if (detail::b32z_lut.from_b32z(c) == 0 && !(c == 'y' || c == 'Y'))
             return false;
     }
@@ -140,15 +140,14 @@ constexpr bool is_base32z(std::string_view s) { return is_base32z<>(s); }
 /// are): which means "yy", "yb", "yyy", "yy9", "yd", etc. all decode to the same 1-byte value "\0".
 template <typename InputIt, typename OutputIt>
 void from_base32z(InputIt begin, InputIt end, OutputIt out) {
-    using Char = decltype(*begin);
+    static_assert(sizeof(decltype(*begin)) == 1, "from_base32z requires chars/bytes");
-    static_assert(sizeof(Char) == 1, "from_base32z requires chars/bytes");
     uint_fast16_t curr = 0;
     int bits = 0; // number of bits we've loaded into val; we always keep this < 8.
     while (begin != end) {
-        curr = curr << 5 | detail::b32z_lut.from_b32z(*begin++);
+        curr = curr << 5 | detail::b32z_lut.from_b32z(static_cast<unsigned char>(*begin++));
         if (bits >= 3) {
             bits -= 3; // Added 5, removing 8
-            *out++ = static_cast<Char>(curr >> bits);
+            *out++ = static_cast<uint8_t>(curr >> bits);
             curr &= (1 << bits) - 1;
         } else {
             bits += 5;

lokimq/base64.h

@@ -77,7 +77,7 @@ static_assert(b64_lut.from_b64('/') == 63 && b64_lut.from_b64('7') == 59 && b64_
 /// Converts bytes into a base64 encoded character sequence.
 template <typename InputIt, typename OutputIt>
 void to_base64(InputIt begin, InputIt end, OutputIt out) {
-    static_assert(sizeof(*begin) == 1, "to_base64 requires chars/bytes");
+    static_assert(sizeof(decltype(*begin)) == 1, "to_base64 requires chars/bytes");
     int bits = 0; // Tracks the number of unconsumed bits held in r, will always be in {0, 2, 4}
     std::uint_fast16_t r = 0;
     while (begin != end) {
@@ -130,21 +130,21 @@ inline std::string to_base64(std::string_view s) { return to_base64<>(s); }
 /// but only at the end, only 1 or 2, and only if it pads out the total to a multiple of 4.
 template <typename It>
 constexpr bool is_base64(It begin, It end) {
-    static_assert(sizeof(*begin) == 1, "is_base64 requires chars/bytes");
+    static_assert(sizeof(decltype(*begin)) == 1, "is_base64 requires chars/bytes");
     using std::distance;
     using std::prev;
 
     // Allow 1 or 2 padding chars *if* they pad it to a multiple of 4.
     if (begin != end && distance(begin, end) % 4 == 0) {
         auto last = prev(end);
-        if (*last == '=')
+        if (static_cast<unsigned char>(*last) == '=')
             end = last--;
-        if (*last == '=')
+        if (static_cast<unsigned char>(*last) == '=')
             end = last;
     }
 
     for (; begin != end; ++begin) {
-        auto c = *begin;
+        auto c = static_cast<unsigned char>(*begin);
         if (detail::b64_lut.from_b64(c) == 0 && c != 'A')
             return false;
     }
@@ -169,12 +169,11 @@ constexpr bool is_base64(std::string_view s) { return is_base64(s.begin(), s.end
 /// the last 4 bits of the last character are essentially considered padding.
 template <typename InputIt, typename OutputIt>
 void from_base64(InputIt begin, InputIt end, OutputIt out) {
-    using Char = decltype(*begin);
+    static_assert(sizeof(decltype(*begin)) == 1, "from_base64 requires chars/bytes");
-    static_assert(sizeof(Char) == 1, "from_base64 requires chars/bytes");
     uint_fast16_t curr = 0;
     int bits = 0; // number of bits we've loaded into val; we always keep this < 8.
     while (begin != end) {
-        Char c = *begin++;
+        auto c = static_cast<unsigned char>(*begin++);
 
         // padding; don't bother checking if we're at the end because is_base64 is a precondition
         // and we're allowed UB if it isn't satisfied.
@@ -185,7 +184,7 @@ void from_base64(InputIt begin, InputIt end, OutputIt out) {
             bits = 6;
         else {
             bits -= 2; // Added 6, removing 8
-            *out++ = static_cast<Char>(curr >> bits);
+            *out++ = static_cast<uint8_t>(curr >> bits);
             curr &= (1 << bits) - 1;
         }
     }

lokimq/hex.h

@@ -63,10 +63,10 @@ static_assert(hex_lut.from_hex('a') == 10 && hex_lut.from_hex('F') == 15 && hex_
 /// Creates hex digits from a character sequence.
 template <typename InputIt, typename OutputIt>
 void to_hex(InputIt begin, InputIt end, OutputIt out) {
-    static_assert(sizeof(*begin) == 1, "to_hex requires chars/bytes");
+    static_assert(sizeof(decltype(*begin)) == 1, "to_hex requires chars/bytes");
     for (; begin != end; ++begin) {
-        auto c = *begin;
+        uint8_t c = static_cast<uint8_t>(*begin);
-        *out++ = detail::hex_lut.to_hex((c & 0xf0) >> 4);
+        *out++ = detail::hex_lut.to_hex(c >> 4);
         *out++ = detail::hex_lut.to_hex(c & 0x0f);
     }
 }
@@ -84,9 +84,9 @@ inline std::string to_hex(std::string_view s) { return to_hex<>(s); }
 /// Returns true if all elements in the range are hex characters
 template <typename It>
 constexpr bool is_hex(It begin, It end) {
-    static_assert(sizeof(*begin) == 1, "is_hex requires chars/bytes");
+    static_assert(sizeof(decltype(*begin)) == 1, "is_hex requires chars/bytes");
     for (; begin != end; ++begin) {
-        if (detail::hex_lut.from_hex(*begin) == 0 && *begin != '0')
+        if (detail::hex_lut.from_hex(static_cast<unsigned char>(*begin)) == 0 && static_cast<unsigned char>(*begin) != '0')
             return false;
     }
     return true;
@@ -115,7 +115,7 @@ void from_hex(InputIt begin, InputIt end, OutputIt out) {
     while (begin != end) {
         auto a = *begin++;
         auto b = *begin++;
-        *out++ = from_hex_pair(a, b);
+        *out++ = from_hex_pair(static_cast<unsigned char>(a), static_cast<unsigned char>(b));
     }
 }
 

tests/test_encoding.cpp

@@ -27,6 +27,17 @@ TEST_CASE("hex encoding/decoding", "[encoding][decoding][hex]") {
 
     REQUIRE( lokimq::from_hex(pk_hex) == pk );
     REQUIRE( lokimq::to_hex(pk) == pk_hex );
+
+    std::vector<std::byte> bytes{{std::byte{0xff}, std::byte{0x42}, std::byte{0x12}, std::byte{0x34}}};
+    std::basic_string_view<std::byte> b{bytes.data(), bytes.size()};
+    REQUIRE( lokimq::to_hex(b) == "ff421234"s );
+
+    bytes.resize(8);
+    bytes[0] = std::byte{'f'}; bytes[1] = std::byte{'f'}; bytes[2] = std::byte{'4'}; bytes[3] = std::byte{'2'};
+    bytes[4] = std::byte{'1'}; bytes[5] = std::byte{'2'}; bytes[6] = std::byte{'3'}; bytes[7] = std::byte{'4'};
+    std::basic_string_view<std::byte> hex_bytes{bytes.data(), bytes.size()};
+    REQUIRE( lokimq::is_hex(hex_bytes) );
+    REQUIRE( lokimq::from_hex(hex_bytes) == "\xff\x42\x12\x34" );
 }
 
 TEST_CASE("base32z encoding/decoding", "[encoding][decoding][base32z]") {
@@ -67,6 +78,16 @@ TEST_CASE("base32z encoding/decoding", "[encoding][decoding][base32z]") {
 
     REQUIRE( lokimq::to_base32z(pk) == pk_b32z );
     REQUIRE( lokimq::from_base32z(pk_b32z) == pk );
+
+    std::vector<std::byte> bytes{{std::byte{0}, std::byte{255}}};
+    std::basic_string_view<std::byte> b{bytes.data(), bytes.size()};
+    REQUIRE( lokimq::to_base32z(b) == "yd9o" );
+
+    bytes.resize(4);
+    bytes[0] = std::byte{'y'}; bytes[1] = std::byte{'d'}; bytes[2] = std::byte{'9'}; bytes[3] = std::byte{'o'};
+    std::basic_string_view<std::byte> b32_bytes{bytes.data(), bytes.size()};
+    REQUIRE( lokimq::is_base32z(b32_bytes) );
+    REQUIRE( lokimq::from_base32z(b32_bytes) == "\x00\xff"sv );
 }
 
 TEST_CASE("base64 encoding/decoding", "[encoding][decoding][base64]") {
@@ -139,4 +160,14 @@ TEST_CASE("base64 encoding/decoding", "[encoding][decoding][base64]") {
 
     REQUIRE( lokimq::to_base64(pk) == pk_b64 );
     REQUIRE( lokimq::from_base64(pk_b64) == pk );
+
+    std::vector<std::byte> bytes{{std::byte{0}, std::byte{255}}};
+    std::basic_string_view<std::byte> b{bytes.data(), bytes.size()};
+    REQUIRE( lokimq::to_base64(b) == "AP8=" );
+
+    bytes.resize(4);
+    bytes[0] = std::byte{'/'}; bytes[1] = std::byte{'w'}; bytes[2] = std::byte{'A'}; bytes[3] = std::byte{'='};
+    std::basic_string_view<std::byte> b64_bytes{bytes.data(), bytes.size()};
+    REQUIRE( lokimq::is_base64(b64_bytes) );
+    REQUIRE( lokimq::from_base64(b64_bytes) == "\xff\x00"sv );
 }